If a company that deals with containers for medical care or foods and drinks faces a medical accident or food poisoning due to insufficient sterilization of containers, the company seriously loses credibility in society. Thus, the internal surfaces of the containers particularly need to be securely sterilized in advanced countries where importance is attached to safety.
At present, as a device for securely sterilizing the internal surface of a container, an internal surface electron beam-irradiating device that can irradiate the internal surface of a container with an electron beam is used. A publicly known internal surface electron beam-irradiating device includes, as shown in FIG. 12, a vacuum nozzle 102 that can be inserted from the opening of a container V so as to emit an electron beam E from an output window 4 (For example, see FIG. 1 of Patent Literature 1). The interior of the vacuum nozzle 102 communicates with an interior of a vacuum chamber (not shown) that is evacuated, thereby forming the electron beam E of accelerated multiple electrons. The electron beam E emitted from the output window 4 provided at tip of the vacuum nozzle 102 is released into the air and collides with air molecules or the like, so that the electron beam F expands as an electron cloud C. The electron cloud C is brought into contact with the internal surface of the container V (a preform in Patent Literature 1), in other words, the electron beam E is emitted to the internal surface of the container V so as to sterilize the internal surface of the container V.
As shown in FIG. 13 (FIG. 2 in Patent Literature 1), Patent Literature 1 also discloses an extension nozzle 105 that is additionally attached, in order to improve the directivity of the electron cloud C, to the tip of the vacuum nozzle 102 shown in FIG. 12.